An exploratory study of anti-wear and friction reduction properties was carried out on the long grinding conditions to investigate the effect of copper nanoparticles as lubricant additive on the vehicle gear oil 500SN.Lubricant performances were tested at different burden and mass percentage of metal nanoparticles under the condition of 1200r/min and 2h.When the burden is 98N and the mass percentage of copper nanoparticles is 0.05%,the property of anti-wear and antifriction of the lubricant oil can be significantly improved,with the wear scar diameter being reduced by 18.1% and the friction coefficient being reduced by 13.6%.When the burden is changed to 392N,the anti-wear performance of the lubricant oil can also be improved with the mass percentage of copper nanoparticles varied from 0.05% to 0.7%,while the capacity of anti-wear and antifriction decreases for the copper nanoparticles as the mass percentage of metal nanoparticles increases.Thus the best percentage of copper nanoparticles as lubricant additive is 0.05% in mass percentage.